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Commit da1f296f authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: make cgroup_path() not print double slashes 

While reimplementing cgroup_path(), 65dff759 ("cgroup: fix
cgroup_path() vs rename() race") introduced a bug where the path of a
non-root cgroup would have two slahses at the beginning, which is
caused by treating the root cgroup which has the name '/' like
non-root cgroups.

 $ grep systemd /proc/self/cgroup
 1:name=systemd://user/root/1



Fix it by special casing root cgroup case and not looping over it in
the normal path.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
parent 26d5bbe5

kernel/cgroup.c

+8 −5
Original line number Diff line number Diff line
@@ -1811,11 +1811,17 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) 
	int ret = -ENAMETOOLONG;

	char *start;



	if (!cgrp->parent) {

		if (strlcpy(buf, "/", buflen) >= buflen)

			return -ENAMETOOLONG;

		return 0;

	}



	start = buf + buflen - 1;

	*start = '\0';



	rcu_read_lock();

	while (cgrp) {

	do {

		const char *name = cgroup_name(cgrp);

		int len;
@@ -1824,15 +1830,12 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) 
			goto out;

		memcpy(start, name, len);



		if (!cgrp->parent)

			break;



		if (--start < buf)

			goto out;

		*start = '/';



		cgrp = cgrp->parent;

	}

	} while (cgrp->parent);

	ret = 0;

	memmove(buf, start, buf + buflen - start);

out: